Balloon catheters are used to perform various medical procedures wherein the balloon is positioned within a body lumen or canal and subsequently inflated. In some of these medical procedures, such as in an angioplasty procedure, the balloon is inflated so as to expand the interior volume of the body canal. In this type of procedure, the balloon is expanded to apply pressure to the interior surface of the body canal to thereby compress any tissue protruding into the canal and thereby enlarge the interior volume thereof. Once the tissue has been compressed, and the body canal widened, the balloon is deflated and removed.
In other types of medical procedures, such as photodynamic therapy (PDT), a balloon catheter is used to align and stabilize the catheter within the body lumen. For example, the balloon catheter may be inflated under low pressure within a body lumen such as the esophagus. A therapeutic fiber optic device is then inserted into the catheter in the vicinity of the balloon. The therapeutic fiber optic device is then used to emit light waves to treat the surrounding tissue. In this procedure, the balloon is used to both align the catheter in the center of the body lumen, and to prevent the catheter from moving during the PDT procedure. The balloon of a typical PDT balloon catheter is relatively large as compared to balloon catheters for use in angioplasty procedures.
An example of a conventional balloon catheter 10 is shown in FIGS. 1-3. As best seen in FIG. 1, the balloon catheter 10 comprises a balloon 12 that is affixed to a catheter 14. The balloon 12 is typically manufactured from a non-elastomeric material (e.g., a semi-rigid or non-compliant material), and includes a distal neck or end 16, a proximal neck or end 18 and a central portion 20. The proximal end 18 of the balloon 12 is secured and sealed to the distal end 22 of the catheter 14 by an adhesive, ultrasonic welding, or some other method. The distal end 16 of the balloon 12 is similarly secured and sealed to an end cap 24 by an adhesive, ultrasonic welding, or some other method. The end cap 24 is affixed to the distal end 26 of a stiffening wire 28, which projects distally from the distal end 22 of the catheter 14. The proximal end 30 of the stiffening wire 28 is secured to a hub 32, which in turn is attached to the proximal end 34 of the catheter 14. The stiffening wire 28 provides lateral and longitudinal support to the distal end 16 of the balloon 12, while also providing a cross-sectional profile that is smaller than that of the catheter 14. This allows the balloon 12 to be folded or collapsed into a smaller profile for passage into and out of the patient.
The hub 32 is configured to be attached to a device, such as a syringe (not shown), that may be manipulated to either inflate or deflate the balloon 12 by injecting a fluid into or withdrawing a fluid from, respectively, the interior volume of the balloon 12. For example, the balloon 12 is inflated by injecting a fluid such as saline through the hub 32 and into the inflation lumen 38 of the catheter 14. The fluid passes through the inflation lumen 38 and into the interior volume of the balloon 12 via one or more apertures 36 in the distal end 22 of the catheter 14. Likewise, the balloon 12 is deflated by withdrawing the fluid from the interior volume of the balloon 12 via the apertures 36 and the inflation lumen 38 of the catheter 14.
Conventional balloon catheters for use in the above-described procedures, including those for use in PDT procedures, have several drawbacks. One such drawback is that conventional balloon catheters often require an inordinate amount of time to be deflated, which must be completely deflated before the balloon can be withdrawn from the patient. This can unnecessarily increase the duration of the procedure, with obvious negative consequences to the patient. Another drawback of conventional balloon catheters is that sometimes the balloon will not deflate completely. When this occurs, it may be difficult or impossible to withdraw the balloon from the patient, particularly when the balloon catheter has been introduced into the patient through an endoscope or other introducer device. Moreover, since it is often difficult to determine if and when a balloon has been completely deflated, the physician or assistant will sometimes attempt to withdraw the balloon from the patient prematurely. If this occurs, then the balloon may become lodged in the endoscope, or may tear and separate into pieces as it is being pulled into the distal end of the endoscope. Balloon catheters for use in PDT procedures, which have relatively large volume balloons, are particularly susceptible to the above-described problems.
FIGS. 2-3 illustrate the conventional balloon catheter 10 of FIG. 1 that will not deflate completely. In particular, and as shown in FIG. 2, as the balloon 12 begins to deflate, the interior surface of the balloon 12 as been drawn inwardly and into contact with the exterior surface of the stiffening wire 28. As further suction is applied to the balloon 12 (via inflation lumen 38), the proximal portion of the balloon 12 completely collapses about the stiffening wire 28, as illustrated in FIG. 3. Once the interior surface of the balloon 12 seals about the stiffening wire 28, any inflation fluid remaining within the distal portion of the balloon 12 becomes trapped within the balloon 12. Any further application of suction merely increases the seal between the interior surface of the balloon 12 and the stiffening wire 28, and will not result in egress of the fluid remaining in the balloon 12.
What is needed is an improved balloon catheter that overcomes the disadvantages of the conventional devices. In particular, what is needed is a balloon catheter that can be quickly and completely deflated to a minimal diameter for ingress and egress through the body's canals and/or an endoscope channel.